The aim of this study was to compare the effects of a dihidropiridin calcium channel blocker amlodipin and a non-dihidropiridin calcium channel blocker verapamil on nephropathy and serum pigment epithelium-derived factor (PEDF) levels of type 2 diabetic patients with hypertension. Forty-one type 2 diabetic patients with uncontrolled hypertension in spite of using angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) were enrolled in the study. The patients were randomized in two groups. First group received amlodipin (5-10 mg/d) and second group verapamil (120-240 mg/d) for 6 weeks. The difference between two calcium channel blocker treatments was investigated by analyzing urinary albumin excretion and plasma PEDF levels of patients at the end of 6 weeks. Urinary microalbumin/creatinine values were decreased in both amlodipin and verapamil groups but it was not statistically significant. Plasma PEDF levels also decreased significantly in both groups at the end of the treatment (p < 0.001 and p < 0.001, respectively). At the end of the treatment there was no significant difference between changes in values of systolic BP, diastolic BP, microalbumin/creatinine and PEDF percentage in both groups (p = 0.788, p = 0.926, p = 0.908, p = 0.140, respectively). PEDF values showed a positive correlation with microalbumin/creatinine, hb A1c, FBS, systolic and diastolic BP levels. It was observed that both of the drugs have similar effects on nefhropathy and PEDF at the end of the treatment. In this study, we suggest that calcium channel blockers may have renoprotective effects by different mechanisms except their antihypertensive effects and this may be important to determine the selection of antihypertensive drug combinations in diabetic nephropathy.
Keywords: Amlodipin; PEDF; nephropathy; type 2 diabetes mellitus; verapamil.